I bought a 12" Swanson aluminum speed square to use for set-up, and my original checks showed that it was pretty accurate. After a while, I started to see some inconsistencies and rechecked it. I had originally just quickly set the lip against the edge of my saw table and checked with my Woodpecker square. A closer check showed that the inside of the lip on one side didn't appear to have been machined - a check with a micrometer showed that the thickness varied from end to end with it thicker in the middle. Based on that, I could get it to match the Woodpecker square depending on which way I rocked it around the high spot. I took it to a little machine shop down the road and they checked it on a Coordinate Measuring Machine (CMM) - sitting on the wide edge, the vertical edge was out .0125" over the 12" length. They set the square up on a milling machine and cut all three edges of the base exactly perpendicular to the other edge - the last two photos are with the lip hooked over the edge of the saw table. A little overkill for woodworking maybe, but I know that the square is right within a fraction of a thousandth and can rely on it when making a set-up - and for only $25, a pretty good deal.

I'm glad you figured this out! I bought the same square a few months ago and also noticed some inconsistency when making finer cuts but wasn't sure which tool was out. So, after reading your post I checked. Sure enough, it's like you described. Unless I happen on a machine shop that'll tweak it for me, I'll relegate it to framing and drop the bucks on something nicer in the shop. Thanks!

Nice size and, at 3/4" thick, works perfectly for squaring the fence to the track. At $25, the price is very reasonable, but be aware that the shipping costs, at ~$19, are almost as much as the square - still way cheaper though than the one that Woodpeckers used to make.

Nice size and, at 3/4" thick, works perfectly for squaring the fence to the track. At $25, the price is very reasonable, but be aware that the shipping costs, at ~$19, are almost as much as the square - still way cheaper though than the one that Woodpeckers used to make.